\begin{table}%t2
\caption{\label{keywords}FITS keywords introduced in this paper.  Each is expressed in units of
meters.}
%\centering
\par
\begin{tabular}{ll}
\hline\hline\noalign{\smallskip}
Keyword & Description\\
\hline
 {\tt CARX\_OBS} & Carrington $x$ coordinate of observer\\
 {\tt CARY\_OBS} & Carrington $y$ coordinate of observer\\
 {\tt CARZ\_OBS} & Carrington $z$ coordinate of observer\\
 {\tt RSUN\_REF} & Value of $R_\odot$ used in determining coordinates\\
\hline
\end{tabular}\vspace*{-1.5mm}
\end{table}